Vertical disc dial and perpetual calender for latitude 47° North. The dial consists of a circular brass disc with an altitude dial on one side and a sunrise/sunset calculator on the other. The perpetual almanac has three rotatable discs set on top of the main disc. The main disc has a date scale and the lowest rotatable disc features a lunar-age scale. Both can be employed for finding the hours of sunrise and sunset and the lengths of the day and night. On the middle rotatable disc there is one small pointer to mark the age of the moon. Beneath this is a hole through which the angular difference (given in hours and minutes) between the hour of the sun and that of the moon can be read from a scale on the first rotatable disc.

This instrument is very similar in style to AST0375, although not of such high quality. It is also similar to a dial by Daniel Weltzien in the National Technical Museum in Prague. The values given for the earliest and latest times of sunrise give a latitude of 47° North (mid-France). The calculator on the reverse of the dial also provides the means for finding the difference between lunar time and solar time for the age of the moon, thus allowing the dial to be used at night. This disc further gives means for calculating the time of high tide, if the time of high water at full moon is known.

For more information regarding this dial please refer to the OUP & NMM catalogue, 'Sundials at Greenwich'.